Problem: Ben ate 3 slices of cake. Luis ate 2 slices. If there were initially 8 slices, what fraction of the cake is remaining?
$\text{fraction of cake eaten} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 5 slices, which leaves 3 out of 8 slices remaining. There is $\dfrac{3}{8}$ of the cake remaining.